U.S. patent application number 10/792051 was filed with the patent office on 2004-09-09 for active noise control using a single sensor input.
Invention is credited to Vaishya, Manish.
Application Number | 20040175003 10/792051 |
Document ID | / |
Family ID | 32930768 |
Filed Date | 2004-09-09 |
United States Patent
Application |
20040175003 |
Kind Code |
A1 |
Vaishya, Manish |
September 9, 2004 |
Active noise control using a single sensor input
Abstract
An active noise control system (20) includes a controller (34)
that receives a signal from a single pressure sensor (36). The
controller (34) estimates an engine speed of an engine (30) and a
throttle position of a throttle valve associated with an air intake
manifold (32). The controller (34) generates a noise control signal
that drives a speaker (38), which responsively generates a noise
attenuation signal. The disclosed embodiment may be used in an
after-market product as it requires minimal interfacing with other
vehicle electronics.
Inventors: |
Vaishya, Manish; (Rochester
Hills, MI) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM
MI
48009
US
|
Family ID: |
32930768 |
Appl. No.: |
10/792051 |
Filed: |
March 3, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60453120 |
Mar 7, 2003 |
|
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|
Current U.S.
Class: |
381/71.4 ;
381/86 |
Current CPC
Class: |
G10K 11/17873 20180101;
G10K 2210/3031 20130101; G10K 2210/1282 20130101; G10K 11/17853
20180101; G10K 11/17821 20180101; G10K 2210/3033 20130101 |
Class at
Publication: |
381/071.4 ;
381/086 |
International
Class: |
A61F 011/06; G10K
011/16; H03B 029/00 |
Claims
I claim:
1. An active noise control system, comprising: a speaker for
generating a noise attenuation signal; and a controller that
controls the speaker with a control signal corresponding to the
noise attenuation signal, the controller using a single air
pressure signal to determine an estimated engine speed and an
estimated throttle position and generating the control signal based
upon the estimated engine speed and the estimated throttle
position.
2. The system of claim 1, including a pressure sensor that is
adapted to be supported in a position to detect air flow in an air
intake manifold, the pressure sensor providing the air pressure
signal.
3. The system of claim 1, wherein the pressure signal has a
frequency and wherein the controller uses the frequency to
determine the estimated engine speed.
4. The system of claim 3, including a level crossing trigger and
wherein the controller determines the estimated engine speed by
identifying an engine firing frequency based upon processing the
pressure signal using the level crossing trigger.
5. The system of claim 3, wherein the controller determines a
dominant order from the pressure signal frequency and determines
the engine speed based upon the dominant order.
6. The system of claim 3, including a band pass filter for
filtering the pressure signal and wherein the controller uses the
filtered signal to determine the engine speed.
7. The system of claim 1, wherein the pressure signal has a DC
component and the controller uses the DC component to determine the
estimated throttle position.
8. The system of claim 7, wherein the DC component is indicative of
a mean airflow and the controller uses the DC component and the
estimated engine speed to determine the estimated throttle
position.
9. A method of controlling an active noise control system,
comprising: estimating an engine speed from an air flow signal;
estimating a throttle position from the same air flow signal; and
generating a noise control signal using the estimated engine speed
and the estimated throttle position.
10. The method of claim 9, including estimating the engine speed
using a frequency of the air flow signal.
11. The method of claim 10, including determining a dominant order
from the frequency and estimating the engine speed based on the
dominant order.
12. The method of claim 10, including estimating the frequency of
the signal and filtering the signal to cancel out a selected range
of frequencies near the estimated frequency and determining the
frequency from the filtered signal.
13. The method of claim 9, including estimating the throttle
position using a component of the air flow signal that indicates a
mean air flow.
14. The method of claim 13, including estimating the throttle
position using the air flow signal component and the estimated
engine speed.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional
Application No. 60/453,120 which was filed on Mar. 7, 2003.
BACKGROUND OF THE INVENTION
[0002] Active noise control systems are well known. One application
for such system is on automotive vehicles. It is possible for
engine noises to be propagated through the air intake manifold in a
manner that they are heard in the passenger compartment of the
vehicle. Typical active noise control systems include a speaker for
generating a noise canceling signal. The speaker produces a sound
that is out of phase with the engine noise to cancel out the noise
to reduce the possibility for it being heard in the passenger
compartment.
[0003] Typical active noise control systems require information
from the vehicle engine for determining the control state and
parameters and for computing the necessary speaker output in real
time. When true cancellation is desired, very accurate information
is required. Such information is acquired in some circumstances
through the vehicle databus or by directly taking analog signals
from various transducers.
[0004] The precise information for noise cancellation provides an
indication abut the phase of the induction sound. Other vehicle
parameters need to be predicted accurately, such as engine crank
position, rotational speed, throttle opening, temperature, etc. The
phase of the induction sound is sensitive to all such
parameters.
[0005] At a minimum, the engine rotational speed and throttle
opening position are required for any useful noise attenuation.
Conventional systems rely upon at least two sensors for such
information.
[0006] Accordingly, multiple inputs to the active noise control
system typically are required. When analog signals are used, that
adds cost and complexity to the system. When digital signals from
the vehicle data bus are used, that adds complexity to the system.
Either of these options require relatively significant interfacing
with existing vehicle electronics.
[0007] Such noise control systems have not been able to be marketed
in an after-market product because they require a significant
interface with existing vehicle electronics. After-market products
that require integrating with other vehicle electronics in that
manner are not practical.
[0008] There is a need for a system that is not so complex or
expensive. Additionally, it would be beneficial to provide a system
that can be sold as an after-market product to provide noise
control capabilities. This invention addresses that need while
avoiding the shortcomings and drawbacks associated with typical
systems.
SUMMARY OF THE INVENTION
[0009] In general terms, this invention is an active noise control
system that relies upon a single sensor signal for estimating an
engine speed and a throttle position that are used for generating a
noise control signal. One embodiment is useful as an after-market
system that can be easily installed on a vehicle not otherwise
having a noise control system.
[0010] One example system includes a speaker for generating a noise
attenuation signal. A controller controls the speaker with a
control signal that corresponds to the noise attenuation signal.
The controller uses a single pressure sensor signal to determine an
estimated engine speed and an estimated throttle position. The
controller generates the control signal based upon the estimated
engine speed and the estimated throttle position.
[0011] In one example, the pressure signal has a frequency and the
controller uses the frequency to determine the estimated engine
speed. The sensor signal also has a DC component that is indicative
of a mean air flow. The controller in one example uses the DC
component of the sensor signal for determining the estimated
throttle position. In one example, the controller uses the
estimated engine speed and the DC component to determine the
throttle position.
[0012] An example method of controlling an active noise control
system includes generating an air flow signal using a pressure
transducer. Estimating an engine speed from the air flow signal and
estimating a throttle position from the same air flow signal
provides information for generating a noise control signal.
[0013] The various features and advantages of this invention will
become apparent to those skilled in the art from the following
detailed description of the currently preferred embodiment. The
drawings that accompany the detailed description can be briefly
described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 schematically illustrates a vehicle incorporating an
example embodiment of, an active noise control system.
[0015] FIG. 2 schematically illustrates selected portions of an
example controller used in an embodiment of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] FIG. 1 schematically shows an active noise control system 20
associated with a vehicle 22. An engine 30 has an air intake
manifold 32 that includes a throttle valve (not illustrated) that
operates responsive to an accelerator pedal position (not
illustrated) in a known manner.
[0017] The active noise control system 20 includes a controller 34
that is adapted to be supported on the vehicle 22. A pressure
sensor 36 is associated with the air intake manifold 32 in a manner
such that it detects air flow through the manifold 32. The sensor
36 provides a signal, which is indicative of the sensed airflow, to
the controller 34. In one example, the pressure sensor 36 is a
transducer that is capable of measuring static and dynamic
components of air pressure in the manifold 32. In one example, the
sensor 36 is mounted in the path of the induction air flow so that
the sensor output is responsive to pulsations caused by intake
valve motion and the main air flow through the manifold duct.
[0018] In another example, the sensor 36 comprises a manifold
absolute pressure (map) or a barometric atmospheric pressure sensor
within the air flow path. One advantage to using a map sensor is
that many vehicles already have one. In one example, the map sensor
provides information regarding a vacuum pressure and has a
sufficient dynamic range and frequency response (up to about 500
Hertz in one example) to satisfy the requirements of active noise
control.
[0019] In the example of FIGS. 1 and 2, the controller 34 provides
power to the sensor 36 so that a single connection to the
controller 34 from the vehicle battery (not illustrated) provides
all the power necessary for operating the controller 34 and the
sensor 36.
[0020] Based upon the sensor signal, the controller 34 generates a
noise control signal that drives a speaker 38 also associated with
the intake manifold 32. The speaker 38 responsively generates a
noise attenuation signal that is out of phase with the engine noise
and, therefore, controls the amount of noise that may be propagated
into the passenger compartment of the vehicle 22 or modifies the
sound that is heard.
[0021] The controller 34 utilizes a single pressure sensor signal
input to estimate an engine speed (i.e., RPM's) of the engine 30
and a throttle position of the throttle valve (not illustrated)
associated with the manifold 32. The signal from the pressure
sensor has a frequency and a DC component. The controller 34
estimates the engine speed based upon the pressure signal
frequency. The controller 34 estimates the throttle valve position
based upon the DC component of the sensor signal.
[0022] As shown in FIG. 2, a level-crossing trigger 40 is
associated with the controller 34. The signal from the sensor 36 is
converted into a digital signal for processing by the controller
34. The engine pulsations occur with every cylinder firing cycle.
Therefore, applying the level crossing trigger 40 on the signal
allows the controller 34 to derive the firing frequency and the
engine rotational speed from the frequency of the signal. Known
filtering techniques can be used to obtain a "cleaner" signal from
the sensor 36.
[0023] The example of FIG. 2 also includes a band pass filter 42
for situations where signal distortion prevents the level-crossing
trigger from working accurately. In one example, the band pass
filter 42 is adjusted to cancel out frequencies in a selected range
from an estimated frequency so that the exact frequency of the
pressure signal can be determined. In one example, the controller
34 identifies a dominant order and uses that to estimate the engine
speed.
[0024] In an example where the sensor 36 comprises a map sensor,
the controller 34 uses the pulsation or frequency from the sensor
signal, which is typically filtered out from the map sensor output
because it is considered undesirable for conventional applications
for estimating the engine speed. In other words, one example
controller 34 uses a feature of a map sensor signal that is
otherwise considered useless.
[0025] The controller 34 estimates the throttle position based upon
the mean air flow through the manifold 32. A DC component of the
pressure sensor signal is indicative of the mean air flow. Digital
or analog filtering is used in one example to filter the pressure
sensor signal to obtain the DC value.
[0026] The controller 34 in one example uses known relationships
between air flow, throttle position and engine speed to estimate
the throttle position. The estimated engine speed, which is derived
from the frequency of the pressure signal as described above, and
the DC component, which indicates the mean air flow, provide
information to the controller 34 to use such known relationships to
estimate the throttle position.
[0027] The controller 34 uses the estimated engine speed and
estimated throttle position along with known techniques for
generating the noise control signal. In one example, the controller
34 has a look up table indicating relationships between air flow,
throttle position and engine RPM and another look up table with
noise control signal values corresponding to estimated engine
speeds and estimated throttle positions.
[0028] A disclosed embodiment may be used as an after-market noise
control product for vehicles. Having a single sensor input to the
controller eliminates the requirement for the controller 34 to
interface with other vehicle electronics. In one example, the
after-market product includes the pressure sensor 36 to be mounted
in an appropriate position relative to the air intake manifold 32.
In another example, the after-market product includes only the
speaker 38 and the controller 34 and relies upon a signal from an
existing manifold absolute pressure (MAP) sensor already on the
vehicle. In either situation, a power amplifier, which can be
powered through the controller, for driving the speaker allows for
a single power connection to provide all necessary power from a
vehicle battery for powering the controller 34, the sensor 36 and
the speaker 38.
[0029] The preceding description is exemplary rather than limiting
in nature. Variations and modifications to the disclosed examples
may become apparent to those skilled in the art that do not
necessarily depart from the essence of this invention. The scope of
legal protection given to this invention can only be determined by
studying the following claims.
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